The conventional muzzle-loading rifle includes a barrel which extends forwardly from a receiver, the rearward end of the barrel having a breech which receives propellant and a projectile. A breech plug is threadably mounted in the receiver and seals the rearward end of the barrel, and the breech, to prevent blow-back of gases upon ignition of the propellant within the breech.
In many muzzle-loaders, a nipple is mounted in the rear end of the breech plug with a projecting rearward end adapted to receive a percussion cap thereon. When struck by a hammer, the percussion cap is fired and ignition sparks travel through a central bore the length of the nipple to ignite the propellant in the breech.
One problem with existing nipples for muzzle loaders is in maintaining the percussion caps on the nipple while hunting, especially when firing in adverse weather conditions. Improper seating of the percussion cap on the nipple commonly causes misfires.
Another common problem with prior art muzzle loader nipples is the use of vent holes in the side of the nipple in order to expand/breakup the cap after firing. These vent holes weaken the nipple, causing the nipple to deform after multiple firings, thereby resulting in improper seating of the percussion cap or an inability to put the cap on the nipple.